w10 micro

Question 1

nutrient media

Answer 1

support growth of microbes

Question 2

enriched meda

Answer 2

nutrient media-blood or serum have even added to enhance growth.
-blood agar and chocolate agar are enriched media

Question 3

selective media

Answer 3

• dyes
• antibiotics
• chemicals
• inhibit growth of most mircroorganisms other than specific CLINICALLY SIGNIFICANT microorganisms.
  ex: mannitol salt selective inhibits most microbes due to high salt: allows growth of staphylococcus media

Question 4

differential media

Answer 4

substances or indicators that will differentiate one type of bacteria from another.
ex: macConkey agar is selective and differential. -prevents growth of skin bacteria but allows growth of enteric bacteria – enteric bacteria differentiated by the way they ferment lactose in the media. - lactose fermenters turn pink, non lactose fermenters don’t change colour.

Question 5

chrome agar

Answer 5

differential nutrient medium that allows bacteria species to grow in different colours

Question 6

MLA QC

Answer 6

• label media with medium type and expiry date
• storing media at appropriate temp
• FIFO
• stored at 4 degrees

Question 7

dehydration media

Answer 7

• purchased
• tightly closed lids so moisture from air isn’t absorbed
• stored at room temp

Question 8

List of ingredients of culture media 14

Answer 8

peptone
meat infusion
sodium chloride
buffers
carbohydrates
pH indicator
Yest extract
agar 
blood
serum
antibiotics
chemicals 
egg media

Question 9

peptone, ingredient of culture media

Answer 9

nutrient source of carbon and nitrogen- mix of amino acids from casein, soy meal and gelatine- soluble in eater and does not coagulate when heated

Question 10

meat infusion ingredient of culture media

Answer 10

-enhance growth of bacteria, made from lean meat -brain, heart, muscle– provides: amino acids, carbohydrates, vitamins, trace elements
not altered by autoclave

Question 11

sodium chloride, ingredient of culture media

Answer 11

make media isotonic-prevents hemolysis in blood agar

Question 12

buffers in culture media

Answer 12

generally phosphate buffers( not in all media)

maintain constant pH from metabolic waste

Question 13

carbohydrates in culture media

Answer 13

glucose added as nutrient

-others added to determine if bacteria are able to ferment them and produce acid

Question 14

pH indicator in culture media

Answer 14

added to media with specific carbs to determine if they have been fermented during growth. (fermentation=metabolic acids=colour change)

Question 15

Yeast extract in culture media

Answer 15

b vitamens

-added in dehydrated form or added as sterile solution after autoclave

Question 16

agar in culture media

Answer 16

seaweed- gel used in solid media.

-heat to boiling to dissolve into solution then poured into agar plates- cools and solidifies at 42 degrees

Question 17

blood in culture media

Answer 17

nutrients promotes variety of bacteria growth

• sterile
• sheep or horse
• BAP blood agar plate- whole blood
• CHOC chocolate agar uses lysed blood
• LBA lakes blood agar uses blood that has been frozen and thawed to lyse red blood cells

Question 18

serum in culture media

Answer 18

nutrient to some special media

-from bovine or horse and collected aseptically or filtered to remove bacteria

Question 19

antibiotics in culture media

Answer 19

• inhibit growth of certain microbes (selective)

- heat sensitive or LABILE antibiotics are filtered to remove bacteria and a added as a sterile solution after autoclave

Question 20

chemicals in culture media

Answer 20

make the selective or differential

Question 21

egg media

Answer 21

used to grow tubercle bacilli

Question 22

labelling of media

Answer 22

labelled with type of medium and expiration date

preparation date may be included

Question 23

sterilizing with microbiological filters

Answer 23

filters: sterilize heat sensitive ingrediants

membrane filters: cellulose esters or plastic polymers- filters with variety of pore sizes: filters with large pores will remove bacteria, small pores will remove viruses

-most use gravity and negative pressure or positive pressure may be used to force fluid through filter

Question 24

how does moist heat kill microorganisms?

Answer 24

kills by coagulation of microbial portents

• coagulation results in break of hydrogen bonds holding protein together, once bonds broken no longer alive
• requires heat and moisture

Question 25

no longer viable meaning

Answer 25

no longer alive

Question 26

temperature and killing microbes

Answer 26

- boiling and free flowing steam effective with proteins - max temp 100 degrees celsius - some spores can live-extend time or temp

Question 27

how can sterilization be accomplished in a short amount of time

Answer 27

steam under pressure and a high temperature

Question 28

what is a steam autoclave

Answer 28

large insulated pressure cooker -contorls temp and pressure | -higher pressure of steam results in higher temp

Question 29

temperatures and pressure of autoclave

Answer 29

15 pounds of pressure psi 121 degrees celsius 20 pounds of pressure psi 126 degrees celsius 30 pounds of pressure psi 135 degrees celsius ** most labs operate at 15 pounds of pressure and a temp of 121 degrees celsius for 15 minutes

Question 30

what does condensation of steam in autoclave do?

Answer 30

1. condenses to a smaller volume causing more steam to be drawn into items being sterilized---PENETRATION 2. steam condenses, latent heat of condensation (heat that went into the production of steam) is released , the heat and the moisture coagulates microbial protein-STERILIZATION

Question 31

parts of an autoclave

Answer 31

jacket- steam filled, surrounds chamber, insulation- keeps constant temp, **heat from jacket allows autoclave to dry after sterilization since steam removed from chamber but not jacket Chamber-steam entering diverted by baffle to prevent direct hit on cool objects. - air and water heavier than steam removed by discharge channel ejector valve-allows water and air to leave, traps steam resulting in pressure buildup door-lock device-wont open if pressure in chamber pressure gauge thermometer-located below chamber in discharge channel- if temp is 121 in discharge channel it would be 121 in chamber - monitor temp carefully- critical for killing microbes

Question 32

liquids in autoclave

Answer 32

- leak proof container that can withstand heat- pyrex -plastics melt - no plastics =melt - lids: -screw caps LOOSE -cotton plugs -caps hard plastic or metal - container should have room for expansion during sterilization -filled to 80%

Question 33

glassware and autoclaving

Answer 33

pipettes-cotton or wool in top can be autoclaved if contaminated. test tube- use proper closures (cotton plugs, metal caps, plastic caps) beakers/cylinders/bottles-tops covered- brown wrapping paper and held inlace with autoclave or masking tape

Question 34

biohazardous waste and autoclave

Answer 34

microbiology cultures are autoclaved before disposal- rendered non-viable and safer for transport. culture media, petri plates and tubes are collected in special plastic autoclave bags or buckets

Question 35

autoclave cycles

Answer 35

- usual temp 121 - time 15 mins-** large volumes require longer heating periods - 1500ml in a 2000 ml flask would need 30 mins to autoclave - exhaust cycle-steam removed from chamber by fast or slow exhaust